COB packaging optical device and assembling method thereof

Abstract

The invention relates to the technical field of optical communication, and provides a COB packaging optical device which comprises a light emitting assembly, a light receiving assembly and a PCBA board and further comprises a first heat dissipation structure and a second heat dissipation structure, the light receiving assembly and the light emitting assembly are separated by the PCBA board and arranged on the upper board face and the lower board face of the PCBA board respectively, and the first heat dissipation structure and the second heat dissipation structure are arranged on the PCBA board. The light receiving assembly is arranged on the first heat dissipation structure, and the light emitting assembly is arranged on the second heat dissipation structure. The invention further provides an assembling method of the COB packaging optical device. The light receiving assembly and the light emitting assembly are directly arranged on the upper side and the lower side of the PCB, hollowing and sinking modes are not adopted, the technical problems that in the prior art, a QDD cannot complete 8-channel transmission, or the area of a PCBA and the overall size of a module must be increased to provide a packaging space for an RX element to form larger OSFP packaging can be solved, meanwhile, through the arrangement of the heat dissipation structure, the heat dissipation efficiency is improved, and the service life of the module is prolonged. And the heat dissipation performance can also be improved, so that the QDD packaging optical module with high speed and high integration level is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communications, and in particular to a COB packaged optical device and an assembling method thereof. Background Art

[0002] The single-channel transmission rate of lasers, TIAs, PDs, and DSP chips has been increased to 200Gpb / s per channel, and the transmission rate of optical modules has also gradually increased to 800G and 1.6T, which has put forward higher requirements on the integration, package size, link impedance continuity, heat dissipation, and reliability of transceiver optical modules.

[0003] Currently, most 800G or 1.6T optical modules are compact and also use COB packaging, especially COC and PCBA use bonded links, such as Figure 1 As shown, the PCBA needs to be hollowed out and the COC needs to be sunken flush with the PCBA surface to achieve better impedance matching and reduce point reflections and losses. This packaging method cannot enable QDD to complete 8-channel (1.6T rate) transmission. Alternatively, the PCBA area and the overall module size must be increased to provide packaging space for RX components to form a larger OSFP package. Therefore, 800G and 1.6T optical modules are generally packaged in OSFP. At the same time, the COC sinking method makes the heat dissipation surface of the TX component different from the actual heat dissipation surface of the module, resulting in poor TX heat dissipation performance and increased module power consumption. As the single-channel rate increases, the gold wire bonding length must be at least 200μm, which will reduce the electrical signal tolerance of the entire link and reduce the overall module yield. Similarly, for the RX side, as the single-channel rate increases, the traditional gold wire bonding method needs to be upgraded and optimized to a flip chip packaging process to reduce electrical loss. Summary of the Invention

[0004] The object of the present invention is to provide a COB packaged optical device and an assembly method thereof, which can at least solve some of the defects in the prior art.

[0005] To achieve the above-mentioned objectives, an embodiment of the present invention provides the following technical solution: a COB-packaged optical device, comprising an optical emitting component, an optical receiving component, and a PCBA board, and also comprising a first heat dissipation structure and a second heat dissipation structure, wherein the optical receiving component and the optical emitting component are separated by the PCBA board, and the optical receiving component and the optical emitting component are respectively arranged on the upper and lower surfaces of the PCBA board, the optical receiving component is arranged on the first heat dissipation structure, and the optical emitting component is arranged on the second heat dissipation structure.

[0006] Furthermore, the optical transmission assembly includes a laser, a collimating lens, a multiplexer, a first optical fiber lens, an isolator, and a first pin assembly with a pigtail, which are sequentially arranged along the optical path.

[0007] Furthermore, the optical transmission component also includes a silicon adapter board, which is used to connect the PCBA board and the laser.

[0008] Furthermore, the optical receiving assembly includes a second pin assembly with a pigtail, a second optical fiber lens, a demultiplexer, a lens array, a prism and a detector, which are sequentially arranged along the optical path.

[0009] Furthermore, the current signal converted by the detector is amplified by a transimpedance amplifier, and a first heat sink is provided on the transimpedance amplifier.

[0010] Furthermore, a protective cover is provided on the light receiving component.

[0011] Furthermore, the first heat dissipation structure includes a first aluminum nitride gasket, and the light receiving component is arranged on the first aluminum nitride gasket.

[0012] Furthermore, the second heat dissipation structure includes an aluminum nitride support pad, a second aluminum nitride gasket and a second heat sink. The light emitting component and the aluminum nitride support pad are both arranged on the second aluminum nitride gasket, and the second aluminum nitride gasket is arranged on the second heat sink.

[0013] An embodiment of the present invention provides another technical solution: a method for assembling a COB packaged optical device, which is used for assembling the above-mentioned COB packaged optical device, comprising the following steps:

[0014] S1, mounting the optical emitting component and the optical receiving component;

[0015] S2, fix the aluminum nitride support pad by coupling the nozzle and glue;

[0016] S3, solder the silicon adapter board, DSP, transimpedance amplifier, and detector to the PCBA board, and plant gold balls on the silicon adapter board;

[0017] S4, complete the alignment and connection between the gold balls on the silicon transfer board and the COC substrate at the transmitter end;

[0018] S5, fixing the light receiving assembly on the PCBA board and encapsulating the optical element of the light receiving assembly with a protective cover;

[0019] S6, applying buffer glue on the optical fiber retention points of the optical transmitting component and the optical receiving component, and adding reinforcing glue on the aluminum nitride support pad of the optical transmitting component;

[0020] S7, attach a heat sink to the outside of the module.

[0021] Furthermore, in the S4 step, glue is applied to the positions of the PCBA board and the aluminum nitride support pad, the PCBA board is clamped on the heating fixture, and the suction nozzle with heating function clamps and adsorbs the light emitting component, and the upper and lower camera image devices of the device are used for positioning to complete the alignment and connection between the gold ball on the silicon adapter board and the COC substrate at the transmitting end.

[0022] Compared with the prior art, the present invention has the following advantages: the optical receiving component and the optical transmitting component are directly arranged on the upper and lower sides of the PCB board without hollowing out or sinking, which can avoid the technical problems in the prior art that QDD cannot complete 8-channel transmission, or that the PCBA area and the overall size of the module must be increased to provide packaging space for the RX component to form a larger OSFP package. At the same time, through the setting of the heat dissipation structure, the heat dissipation performance can also be improved to realize a high-speed, highly integrated QDD packaged optical module. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the local structure of a traditional optical device (showing the sunken COB and sunken package);

[0024] Figure 2 An exploded diagram of a COB packaged optical device provided by an embodiment of the present invention;

[0025] Figure 3 A schematic structural diagram from a first perspective of a silicon adapter board for a COB packaged optical device provided in an embodiment of the present invention;

[0026] Figure 4 A schematic structural diagram from a second perspective of a silicon adapter board for a COB packaged optical device provided by an embodiment of the present invention;

[0027] Figure 5 A schematic structural diagram of a COC transmitting end of a COB packaged optical device provided in an embodiment of the present invention;

[0028] Figure 6 A schematic structural diagram of a gold ball of a COB packaged optical device provided by an embodiment of the present invention;

[0029] Figure 7 A schematic structural diagram of an optical transmission assembly of a COB packaged optical device provided by an embodiment of the present invention;

[0030] Figure 8 A schematic diagram of the structure of the optical transmitting component, optical receiving component and PCBA board of a COB packaged optical device provided by an embodiment of the present invention;

[0031] Figure 9 A schematic diagram showing a top view of the optical receiving assembly of a COB packaged optical device and its PCBA board provided in an embodiment of the present invention;

[0032] In the figure marks: 10-PCBA board; 11-groove; 20-laser; 21-collimating lens; 22-multiplexer; 23-first fiber lens; 24-isolator; 25-first pin assembly with pigtail; 26-silicon adapter board; 27-transmitter COC; 28-gold ball; 30-second pin assembly with pigtail; 31-second fiber lens; 32-demultiplexer; 33-lens array; 34-prism; 35-detector; 36-transimpedance amplifier; 37-first heat sink; 38-protective cover; 40-first aluminum nitride gasket; 50-aluminum nitride support pad; 51-second aluminum nitride gasket; 52-second heat sink. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] See also Figures 2 to 9 An embodiment of the present invention provides a COB packaged optical device, including an optical transmitting component, an optical receiving component, and a PCBA board 10, and also including a first heat dissipation structure and a second heat dissipation structure. The optical receiving component and the optical transmitting component are separated by the PCBA board 10, and the optical receiving component and the optical transmitting component are respectively arranged on the upper and lower surfaces of the PCBA board 10, the optical receiving component is arranged on the first heat dissipation structure, and the optical transmitting component is arranged on the second heat dissipation structure. In this embodiment, the optical receiving component and the optical transmitting component are directly arranged on the upper and lower sides of the PCB board without hollowing out or sinking. This can avoid the technical problems in the prior art that the QDD cannot complete 8-channel transmission, or that the PCBA area and the overall size of the module must be increased to provide packaging space for the RX component to form a larger OSFP package. At the same time, by setting the heat dissipation structure, the heat dissipation performance can also be improved to achieve a high-speed, highly integrated QDD packaged optical module.

[0035] See also Figures 2 to 9, refine the above-mentioned first and second heat dissipation structures. The first heat dissipation structure includes a first aluminum nitride gasket 40, and the optical receiving component is disposed on the first aluminum nitride gasket 40. The second heat dissipation structure includes an aluminum nitride support pad 50, a second aluminum nitride gasket 51, and a second heat sink 52. The optical transmitting component and the aluminum nitride support pad 50 are both disposed on the second aluminum nitride gasket 51, and the second aluminum nitride gasket 51 is disposed on the second heat sink 52. A 1.6T transmission rate can be achieved on the QSFP-DD package structure, the heat dissipation area of ​​the optical transmitting component is increased, and the heat dissipation surface of the optical transmitting component is aligned with the heat dissipation surface of the module (DSP), thereby improving the heat dissipation performance of the module. At the same time, it can also effectively dissipate heat for the transimpedance amplifier 36 of the optical receiving component, thereby realizing a high-speed, highly integrated QDD packaged optical module. Preferably, a groove 11 is provided on the PCBA board 10, and the first aluminum nitride gasket 40 is disposed in the groove 11.

[0036] See also Figures 2 to 9 , further refining the above-mentioned optical transmission component, the optical transmission component includes a laser 20, a collimating lens 21, a multiplexer 22, a first fiber lens 23, an isolator 24, and a first pin assembly 25 with a pigtail, which are arranged in sequence along the optical path. The optical transmission component also includes a silicon adapter board 26, which is used to connect the PCBA board 10 and the laser 20. The laser 20 is provided on the transmitting end COC 27. Specifically, the DSP electrical signal on the PCBA board 10 passes through the circuit of the PCBA board 10 and the silicon adapter board 26 to the transmitting end COC 27, controlling the laser 20 on the transmitting end COC 27 to emit an optical signal, which is then coupled to the first pin assembly with a pigtail through the collimating lens 21, the multiplexer 22, the first fiber lens 23, and the isolator 24, converting the electrical signal into an optical signal for transmission. In addition, the silicon adapter board 26 mainly serves to connect the transmitter COC27 and the PCBA board 10. While performing impedance matching, it also integrates the laser 20 filter capacitor to filter the laser 20. The adapter board is mainly made of silicon. Through etching, plating, filling and other processes, the internal routing is designed to achieve the signal link of GSG or GSSG impedance matching between the PCBA board 10 and the transmitter COC27. When the silicon adapter board 26 is mounted on the PCBA board 10, it is attached to the PCBA board 10 together with the DSP chip, transimpedance amplifier 36 and other components. Preferably, the transmitter COC27 is composed of the laser 20 and the substrate, and the gold-tin solder and the substrate are eutectic welded together. After the gold wire bonding is completed, each laser 20 can be subjected to an aging test to screen the chips with qualified reliability. The design of the transmitter COC27 is not limited to this. Figure 5This is just a brief illustration of the electrical signal connection method. The number of pads on the transmitter COC27 matches the number and spacing of pads on the front of the silicon adapter board 26. The substrate material in the transmitter COC27 is generally silicon or aluminum nitride, which has a high heat dissipation coefficient and a thermal expansion coefficient comparable to that of the laser 20, which is conducive to stable operation of the chip; the impedance of the transmitter COC27, silicon adapter board 26, and PCBA board 10 is generally matched to 50Ω. On this basis, signal reflection and insertion loss on the transmitter COC27 can be reduced by adding some through holes, fine-tuning the gold layer pattern, etc. Figure 6 The gold balls 28 are welded together with the silicon adapter plate 26 and the chip. After welding, the gold balls 28 are planted on the silicon adapter plate 26, with 1 to 2 balls planted on each pad. The height of the gold balls 28 is 45 to 50 μm and the ball diameter is 60 to 70 μm. On the other hand, the optical transmitter assembly is assembled - the transmitting end COC27, multiplexer 22, isolator 24, and first fiber lens 23 are patched onto the second aluminum nitride gasket 51 through a patch machine. After the patching is completed, the laser 20 is powered (LD+ and GND) through a probe to couple the first pin assembly 25 with a pigtail, and then coupled to the collimating lens 21; after the coupling is completed, the height of the four receiving end COCs is tested with a suction nozzle. After the test is completed, the aluminum nitride support pad 50 is adsorbed with a suction nozzle, and the distance between the aluminum nitride support pad 50 and the second aluminum nitride gasket 51 is adjusted. The surface of the aluminum nitride support pad 50 is an average of 35um higher than the surface of the receiving end COC, and fixed by UV dispensing. The schematic diagram of the entire optical transmitter assembly is shown in the attached figure. Figure 7 As shown, the aluminum nitride support block 50 is the highest in the entire optical transmitter assembly. Figure 8 , apply UV glue on the position of PCBA board 10 and aluminum nitride support pad 50, place PCBA board 10 on the heating fixture, clamp the light emitting component with a nozzle with heating function, and use the upper and lower camera image equipment of the device to position and complete the alignment and connection between the gold ball 28 on the silicon adapter board 26 and the COC27 substrate of the transmitting end. When the connection is completed, pre-cure the glue on the aluminum nitride support pad 50, then remove the entire device and put it into the box to bake until the glue is 100% cured.

[0037] See also Figures 2 to 9, the above-mentioned optical receiving component is refined, and the optical receiving component includes a second pin assembly 30 with a pigtail, a second optical fiber lens 31, a demultiplexer 3222, a lens array 33, a prism 34 and a detector 35 arranged in sequence along the optical path. The current signal converted by the detector 35 is amplified by a transimpedance amplifier 36, and a first heat sink 37 is provided on the transimpedance amplifier 36. A protective cover 38 is provided on the optical receiving component. Specifically, the external optical signal of the module passes through the second pin assembly 30 with a pigtail, the second optical fiber lens 31, the demultiplexer 3222, the lens array 33 and the prism 34 to reach the detector 35. The detector 35 converts the high-speed optical signal into a current signal, which is amplified by the transimpedance amplifier 36 and then processed by the DSP chip on the PCBA board 10 to complete the photoelectric conversion and signal transmission. As Figure 8 and Figure 9 As shown, the transimpedance amplifier 36 and detector 35 in the optical receiver assembly are soldered to the PCBA 10 along with the DSP, silicon adapter board 26, and other components using a flip chip process. Once the optical receiver assembly is assembled with the PCB, the assembly and detector 35 are coupled together. Specifically, the maximum distance between each component and the bottom of the second aluminum nitride spacer in the optical receiver assembly is maintained within 1.1 mm. Excessive package height would result in thinner external structural components and reduced reliability.

[0038] See also Figures 2 to 9, an embodiment of the present invention provides an assembly method for a COB packaged optical device, which is used for assembling the above-mentioned COB packaged optical device, including the following steps: S1, mounting the optical emitting component and the optical receiving component; S2, fixing the aluminum nitride support pad 50 through a coupling nozzle and glue; S3, welding the silicon adapter board 26, DSP, transimpedance amplifier 36 and detector 35 on the PCBA board 10, and planting gold balls 28 on the silicon adapter board 26; S4, completing the alignment and connection between the gold balls 28 on the silicon adapter board 26 and the COC27 substrate at the transmitting end; S5, fixing the optical receiving component on the PCBA board 10, and using a protective cover 38 to encapsulate the optical element of the optical receiving component; S6, applying buffer glue on the optical fiber retention points of the optical emitting component and the optical receiving component, and adding reinforcing glue on the aluminum nitride support pad 50 of the optical emitting component; S7, attaching a heat sink to the outside of the module. In this embodiment, the specific process is as follows: the optical emitting component is mainly assembled through patch assembly, and the transmitting end COC27 is powered by a probe for active coupling; the optical receiving component is also assembled through patch assembly, and a patch is used to complete the standard part, and the lens array 33 in the optical receiving component and the second pin assembly 30 with pigtail are actively coupled to complete the assembly of the optical receiving component; after the optical part of the optical emitting component is assembled, the aluminum nitride support pad 50 is fixed at a suitable height through a coupling suction nozzle and UV glue, and the thickness of the glue mainly needs to be measured and adjusted by the grating ruler on the suction nozzle to achieve an average height of 35um between the surface of the aluminum nitride support pad 50 and the surface of the transmitting end COC27; by flip The chip process welds the silicon adapter board 26, DSP, transimpedance amplifier 36, detector 35, etc. on the PCBA board 10, and underfills the lower surface of the chip with buffer heat dissipation glue; implants gold balls 28 on the surface of the silicon adapter board 26; applies UV glue at the position of the PCBA board 10 and the aluminum nitride support pad 50, and clamps the PCBA board 10 on the heating fixture. The suction nozzle with heating function clamps and adsorbs the light emitting component, and the upper and lower camera image devices of the device are used to position and connect the gold balls 28 on the silicon adapter board 26 to the transmitting end COC27 substrate; the light receiving component is fixed on the PCBA board 10 through active coupling, and after complete curing, the protective cover 38 is encapsulated above the optical component; buffer protection soft glue is applied on the optical fiber retention points of the light emitting component and the light receiving component, and reinforcing glue is added to the aluminum nitride support pad 50 of the light emitting optical component to increase structural stability; a heat sink is attached to the external structural parts of the module, and the transmitting end COB optical device component is assembled into the module. This embodiment describes a 2*400G or 2*800G implementation. Similarly, it can also be implemented using a 1*1.6T (CWDM8) approach.

[0039] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A COB packaged optical device, comprising an optical transmitter component, an optical receiver component, and a PCBA board, characterized in that: It also includes a first heat dissipation structure and a second heat dissipation structure, the light receiving component and the light emitting component are separated by the PCBA board, and the light receiving component and the light emitting component are respectively arranged on the upper and lower surfaces of the PCBA board, the light receiving component is arranged on the first heat dissipation structure, and the light emitting component is arranged on the second heat dissipation structure.

2. The COB packaged optical device according to claim 1, wherein: The optical emission assembly comprises a laser, a collimating lens, a multiplexer, a first optical fiber lens, an isolator and a first pin assembly with a pigtail, which are arranged in sequence along the optical path.

3. The COB packaged optical device according to claim 2, wherein: The optical transmission assembly further includes a silicon adapter board, which is used to connect the PCBA board and the laser.

4. The COB packaged optical device according to claim 1, wherein: The optical receiving assembly includes a second pin assembly with a pigtail, a second optical fiber lens, a demultiplexer, a lens array, a prism and a detector which are sequentially arranged along the optical path.

5. The COB packaged optical device according to claim 4, wherein: The current signal converted by the detector is amplified by a transimpedance amplifier, and a first heat sink is provided on the transimpedance amplifier.

6. The COB packaged optical device according to claim 4, wherein: A protective cover is provided on the light receiving component.

7. The COB packaged optical device according to claim 1, wherein: The first heat dissipation structure includes a first aluminum nitride gasket, and the light receiving component is arranged on the first aluminum nitride gasket.

8. The COB packaged optical device according to claim 1, wherein: The second heat dissipation structure includes an aluminum nitride support pad, a second aluminum nitride gasket and a second heat sink. The light emitting component and the aluminum nitride support pad are both arranged on the second aluminum nitride gasket, and the second aluminum nitride gasket is arranged on the second heat sink.

9. A method for assembling a COB packaged optical device, characterized in that: The assembly of the COB packaged optical device according to any one of claims 1 to 8 comprises the following steps: S1, mounting the optical emitting component and the optical receiving component; S2, fix the aluminum nitride support pad by coupling the nozzle and glue; S3, solder the silicon adapter board, DSP, transimpedance amplifier, and detector to the PCBA board, and plant gold balls on the silicon adapter board; S4, complete the alignment and connection between the gold balls on the silicon transfer board and the COC substrate at the transmitter end; S5, fixing the light receiving assembly on the PCBA board and encapsulating the optical element of the light receiving assembly with a protective cover; S6, applying buffer glue on the optical fiber retention points of the optical transmitting component and the optical receiving component, and adding reinforcing glue on the aluminum nitride support pad of the optical transmitting component; S7, attach a heat sink to the outside of the module.

10. The method for assembling a COB packaged optical device according to claim 9, wherein: In the S4 step, glue is applied to the positions of the PCBA board and the aluminum nitride support pad, the PCBA board is clamped on the heating fixture, and the suction nozzle with a heating function clamps and adsorbs the light emitting component. The upper and lower camera image devices of the device are used for positioning to complete the alignment and connection between the gold ball on the silicon adapter board and the COC substrate at the transmitting end.

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